The present invention relates to dunnage racks used to store and transport parts, such as automotive parts, and more particularly to a bar used in such racks.
Dunnage racks are widely used in manufacturing to store and transport parts, for example, automotive parts. These racks include a frame and a plurality of horizontal bars supported on the frame. Modular connectors permit the bars to be spaced and positioned in a wide variety of configurations to accommodate different parts to be stored in the rack. A plastic and/or foam insert, generally well known to those having skill in the art, typically is mounted within each bar to engagingly support the parts.
Known dunnage bars are basically of two constructions. A first is extruded of aluminum and includes a T-shaped slot within which the insert is retained. These aluminum bars are relatively expensive. Further, the bars are subject to considerable pilferage because of their value as scrap aluminum.
A second is fabricated of two roll-formed steel pieces as illustrated in FIG. 5 of U.S. Pat. No. 5,605,239. The outer piece is generally C-shaped and includes three closed planar sides and a fourth open side defining a mouth. An inner piece is positioned in the mouth and is generally trough-shaped. The two pieces are nested and then spot-welded together at spaced locations to intersecure the pieces. While this steel bar is less expensive than the extruded aluminum bar, it requires welds to be placed along both longitudinal sides of the dunnage bar. Additionally, the inner and outer pieces can break apart from each other as a result of faulty welds or heavy loads.
A third style one-piece dunnage bar is shown in U.S. Pat. No. 5,605,239. This dunnage bar is fabricated of a single piece of sheet metal roll-formed into a tubular shape, with one side of the dunnage bar including opposing L-shaped flanges shaped to engage a slotted base of a polymeric insert. However, in order to make the dunnage bar from a single piece of sheet metal, the L-shaped flanges are necessarily double-thickness, which results in a tight fold and high material stress at the point where the single wall is bent sharply back upon itself. A problem is that the material in the area of the tight fold can fracture due to high stress concentrations generated at the tight fold during manufacture of the dunnage bar. This reduces the desirability of the dunnage bar since the fractured corners look bad, can cause difficulty in assembling or replacing inserts on the dunnage bars, can reduce a strength of the dunnage bars, can lead to rust and corrosion, and can result in safety issues for workers. The double thickness walls also waste material, since two walls are located where only a single wall is needed. The double thickness walls also create problems with using conventional inserts, since conventional inserts are only adapted to receive L-shaped flanges having a single wall thickness. It is noted that the U.S. Pat. No. 5,605,239 discloses that the double-thickness walls can be made from individual single walls having a half thickness, but this increases the manufacturing cost for making the dunnage bars, or leads to higher raw material costs.
Accordingly, a dunnage bar is desired solving the aforementioned problems and having the aforementioned advantages.
In one aspect of the present invention, a dunnage rack includes a dunnage bar adapted to receive an insert, where the insert is shaped to support parts for material handling purposes, and includes a cushioning portion, a retainer portion, and an interconnecting portion. The dunnage bar includes a tube section made from a single sheet of material. The tube section has a wall with a face surface and has longitudinally extending first and second rows of L-shaped tabs extending from the face surface that are formed from the material of the wall. The wall has apertures corresponding to locations of the L-shaped tabs. The L-shaped tabs defining a channel on the face surface that is adapted to receive the retainer portion and engage the retainer portion in a longitudinal direction. The L-shaped tabs further define an access opening into the channel for receiving the interconnecting portion of the tube section to structurally support the insert on the face surface.
In another aspect of the present invention, a tubular bar adapted to longitudinally receive an insert includes a tube section having four orthogonally-related flat walls. One of the walls has a face surface and has longitudinally extending first and second rows of tabs extending from the face surface that are formed from the material of the tube section. The tube section has apertures corresponding to locations of the tabs, with the apertures being located in spaced-apart positions to maintain a strength of the tube section. The tabs in the first row include legs facing toward the tabs in the second row, such that the first and second tabs define a channel on the face surface that is adapted to receive a retainer portion of an insert. The first and second tabs define an access opening into the channel that is adapted to receive an interconnecting portion of the insert, with the tube section structurally supporting the insert on the face surface.
In another aspect of the present invention, a method includes providing a roll of sheet material suitable for use as a dunnage bar. The method further includes unrolling the sheet material and forming two rows of L-shaped tabs in the sheet material, with the two rows defining a longitudinally engageable channel on the sheet material and an access opening into the channel from a lateral direction. The method still further includes forming the sheet material into a tubular shape, and retaining edges of the sheet material together to permanently fix the tubular shape.
These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.